Up-conversion fluorescence and thermal optical bistability in Gd ₂O₃: 10% Yb³, 0.5% Tm³

Through a co-precipitation method Gd(OH)₃: 0.5% Tm³, 10% Yb³ powder was synthesized. After sintering at different temperatures, the as-prepared Gd(OH)₃: 0.5% Tm³, 10% Yb³ powder was changed into cubic and monoclinic phase Gd ₂O₃: 0.5% Tm³, 10% Yb³ phosphors. Crystalline phases and morphologies of as-prepared powder and phosphors were characterized by X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM). Up-conversion (UC) fluorescence spectra of Gd ₂O₃: 0.5% Tm³, 10% Yb³ phosphors were recorded by a fluorescence spectrophotometer with a 980 nm continuous wave laser diode as the excitation source. Fluorescence decay behaviors of the phosphors were measured by exciting with 980 nm from an optical parametric oscillator (OPO) pumped by a pulsed Nd: YAG laser with a pulse duration of 10 ns and a repetition frequency of 10 Hz, and the signal was recorded using a monochromator and an oscillograph. Phase and excitation power dependent UC fluorescence properties of the phosphors were studied in detail in the article. Interestingly, the cubic phase phosphors presented thermal optical bistability phenomena. The fluorescence dynamic analysis indicated that rise and decay processes existed in the phosphor UC fluorescence.